As I've noted before, I wish I could keep all relationships I've ever had in ways that are strong and good, but over time, as we know, relationships change for all kinds of reasons, and we have to acknowledge and deal with those changes.
Time, Place, and Obligations
Most of all, relationships change due to time, place, and obligations. The biggest change to my relationships occurred when I had young children. You're so busy as a parent and many of us are quite strapped during those years with respect to time and money that your relationships change and suffer. I remember those days and the fact that we had almost no free time and few resources too. I made a decision during those years that it would be family first, and I'm mostly satisfied with that, however, I wish I had made time to revise relationships in ways that kept some old time relationships alive with once-a-year get togethers.
Differing values and priorities
Relationships sometimes change because of differing values and priorities. For example, if a friend is operating in ways that go against your values in a significant way, you may have to end the relationship since continuing the relationship makes you an accomplice to behaviors you dramatically disagree with.
Location
When you and friends are distanced by miles, the relationship will be impacted. Although sometimes distance is exactly why a relationship stays in place--distance creates a natural sporadic visiting schedule and also doesn't find you comparing day-to-day choices. This distance could actually help to preserve a relationship in some instances.
Job demands
Some jobs demand more of you than other jobs, and demanding jobs can impact relationships.
As I age, I value relationships more than ever. I want to nurture the good relationships I have with just-right expectations, get togethers, manners, conversations, and all intersections. As people we need each other and profit from our good relationships. Relationships will change, and we can weather those changes positively with a good mindset and responses. Onward.